Objectives: 1) To determine the haematological and biochemical modifications that occurs during and after a stay in moderate altitude. 2) To establish controls for staying and training at that altitude. Materials and methods: A) Subjects: We have studied 11 female volleyball players of the Granada University team (which plays in the Spanish Honours Division). Their ages were between 17 and 29, and they had an average height of 70.94 in and a weight of 154.76 lbs. B) Design: Analysis intra group (“n” parameters and 6 weeks of duration). Phase 1: Two weeks’ training at 2.296,59 ft. altitude (Granada). Phase 2: Two weeks’ training at 7.611,55 ft altitude (in the Sierra Nevada Centre of High Performance). Phase 3: Two weeks’ training in Granada again. Once a week, samples of blood and urine were taken for haematological and biochemical analysis. C) Parameters: Complete haemogram, Globular Sedimentation Speed, leucocitary formula, glucose, urea, creatinine, transaminases (GOT,GPT,GGT), direct bilirubin, indirect and total, total cholesterol, HDL, LDL, triglyceride, uric acid, amylase, alkaline phosphatase, calcium, sodium, potassium, chlorine, urinary volume, urinary density and potential osmotic pressure. Results: In altitude (7.611,55 ft.) leukocytosis is 22% greater than at 2.296,59 ft, not observing appreciable modifications in the specific parameters of haemogram, haemoglobin or haematocrit. In altitude we observe significant increments of up to 24.5% of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH), without significant statistical variations in the rest of the values. More important conclusions: Significant variations were only observed in the variables CPK and LDH.